Despite considerable recent interest, surprisingly little is known regarding the mechanisms of the weight reducing qualities of smoking. While many studies have been conducted, each typically chose only a portion of the energy balance picture for examination or covered a very short span of time. Thus, these investigations have yielded equivocal results, with studies divided as to whether smoking has its effects on diet (or components of the diet), metabolic rate, physical activity, or some combination of these factors (US DHHS, 1990). To date, no study has evaluated the effect of smoking on the entire energy balance equation simultaneously in a large sample. There is, however, good evidence that the weight-suppression effect of smoking may be affected by both gender and race. In recent years, empirical investigations have reported that women gain more weight than men following smoking cessation, that Blacks gain more postcessation weight than Whites (Klesges et al., 1992; Klesges & Klesges, 1992; Williamson et al., 1991), and, in an analysis of the more than 10,000 adults in the NHANES II data set, that the weight-controlling properties of continued smoking are more pronounced in women than in men (Klesges, Klesges, & Meyers, 1991). Further, Black women appear to be the most vulnerable to postcessation weight gain, with a recent report that Black women gained an average of 27 pounds postcessation (Cutter, Klesges, & Klesges, 1992). Although White women seem to be deriving the most weight-suppressing benefit from smoking, they also seem to be at risk (relative to men) for postcession weight gain. Black women do not appear to derive weight-suppressing benefits from smoking, but they are at the very highest risk for postcessation weight gain. Given the potential effects of smoking and race on energy balance, we propose the following specific aims: (1) To carefully evaluate the role of smoking on the dietary intake, physical activity, and metabolic rate, relative to nonsmokers; and (2) To determine the differential effects of smoking and race on the energy balance of Black and White women.